With increased attention and regulatory resources being directed to the establishment and maintenance of uncontaminated rivers, lakes, and ground water, it has become imperative for the producer of wastewater to employ a treatment system which avoids the introduction of prohibited levels of contaminants into the environment.
In many states groundwater control regulations of exacting strictness have been enacted. Commonly, these regulations require the immediate report and remediation of any discharges of organic and inorganic waste, soluble heavy metals, petroleum products, or bacteriologically contaminated materials which exceed regulatory levels. Although it is always an option to transport the contaminated wastewater to an outside authorized disposal facility, such transportation is usually prohibitively expensive due to the large volume of wastewater involved. Furthermore, transportation of waste deemed hazardous may require prior authorization and permitting from regulatory authorities.
Alternatively, various industrial wastewaters containing harmful or hazardous substances can be properly pretreated for resource recovery or pollution load reduction before being discharged to municipal sewers or receiving waters. However, if a wastewater stream is sufficiently cleaned so that it can be discharged into the environment, then it may as well be processed so that it may be recycled and reused in the particular industrial process that generates the wastewater.
Wastewaters often contain constituents such as pesticides, organics, dirt, heavy metals, microorganisms, and soluble and insoluble inorganics, for instance. Many conventional unit processes address the elimination of these contaminants. For example, some of the unit processes used in the prior art include chemical coagulation, flocculation, oxidation, sedimentation clarification, flotation clarification, air stripping towers, granular activated carbon filtration, sand filtration, ozonization, ultraviolet light treatment, chlorination, reverse osmosis, ultrafiltration, microfiltration, ion exchange, distillation, etc. See, e.g. U.S. Pat. Nos. 3,855,124; 3,945,918; 4,028,233; 4,108,768; 4,224,148; 4,340,473; 4,425,238; 4,659,462; 5,059,317; 5,071,587; 5,077,314; 5,178,755; 5,238,579; and 5,256,299. The disclosures of these patents referred to above are incorporated by reference as if fully set forth herein.
Citrus, fruit, and vegetable packing facilities are a large user of water, and concomitantly a large generator of wastewater, since large amounts of water must be used to remove dirt, herbicides, fungicides, and pesticides from the skin of fruits and vegetables prior to packing and shipping to stores or canning facilities. In general, ozonized water is desirable in the food processing environment because of its disinfecting properties. Since a large amount of water must be used in such operations, significant savings can be realized if this water can be cleaned up and reused.
However, each of the aforementioned unit processes can only partially purify this contaminated water. In general, a feasible water treatment system must involve the use of several unit processes in order to sufficiently clean up the water so that it can be recycled. Such a treatment system is often custom designed and is usually expensive.
Accordingly, a need exists for an economical process and apparatus for cleaning and recycling the wash water used in citrus and vegetable packing facilities.